The cost of English becoming the world language is that everybody has a different way to say it! Our spelling has become extremely irregular. While you can look at Old English and make a reasonable guess at pronunciation, in Modern English there are thousands of words where “you just have to know it”.
Old English had fairly regular spelling. You can make a fair guess at sight reading OE. The scribe wrote down what he heard spoken. See if you can pronounce this 10th century preface to a bible translation.
Ælfric munuc grēt Æðelwærd ealdormann ēadmōdlīce. Þū bǣde mē, lēof, þæt ic sceolde ðē āwendan of Lēdene on Englisc þā bōc Genesis: þā þūhte mē hefigtīme þē tō tīðienne þæs, and þū cwǣde þā þæt ic ne þorfte nā māre āwendan þǣre bēc būton tō Isaace, Abrahāmes suna, for þām þe sum ōðer man þē hæfde āwend fram Isaace þā bōc oð ende.
Ælfric had most of the Roman letters we now use. There are also modified runes Þ and ð, which we now write “th”. We do not currently pronounce the vowel <æ> in hæfde, but the queen used to say it in upper-class RP hæt. There is an letter combination rule in Englisc that we now write with “sh”. Finally, modern editors add a macron in grēt to show that it is long, though the OE scribes did not use it. That is about all you need to know to read the above passage. Alfred was able to achieve a West Saxon written standard for OE.
A problem that was already arising is that speech was diverging from writing in two consonants. The stop /g/ was sometimes being as in “ye”. The modern reader can guess this if the next vowel is an /e/ or /i/, though that would not be true for Genesis. Scribes started putting a dot in ġif to show that it was now “yif”. The was also change in the sound as in “loch” or “Bach” before /e/ or /i/ so the first person pronoun was written iċ.
Middle English was non longer standardised, so a huge number of pronunciation differences arose. Go to https://quod.lib.umich.edu/m/middle-english-dictionary/dictionary and try the common word ben, ‘to be’.
Disappearing sounds were the next problem, of which “-ugh” is the most troublesome: the velar fricative “ch” disappeared from dialects of English except Scots, but persists in the spelling. We lost the front vowel written with a “y” but pronounced “ü” as in Drychtin ‘god’. Then we stopped pronouncing the /w/ in “who”, the /k/ in “knight” and the /g/ in “gnome”. In the last century or two most people (but not Americans) dropped the in “beer” and “fire”.
English vowels move around a lot. The Great Vowel Shift started soon after Chaucer. All the long vowels of standard English changed between the time of Chaucer and that of Shakespeare. Chaucer lived in what would have sounded like a hoos, with his weef, and hay would romance heer with a bottle of weena, drunk by the light of the moan. Shakespeare would have pronounced them in more or less the modern way, as house, wife, he, her, wine, and moon. Some regional accents did not follow the main trend, as we shall see with Black Country dialect. There is a general rule for this: each front vowel moves one step closer; the closest vowel becomes a diphthong. The UCL linguist John Wells argues that these shifts have affected all dialects of English, at least in respect of front vowels. The printing press produced a standard bible, which had the effect of preserving spelling and resisting speech change.
If we could rationally plan a spelling system, what would it have to achieve? We need 24 letters to represent our consonant phonemes. Our 26-letter alphabet gives us 21. Three of these are redundant: “q”, “k” and “x” are variants of “k”. Normans did not want non-Latin characters (ȝ, ð, þ) so used the digraph “th” for the last two. This is mostly acceptable, but gives a problem with “mishit” and “gasholder”. The bigger problem comes with vowels. We need to represent 20 vowel phonemes with five vowel letters. (Recall that the phoneme is a unit of speech meaning, not a sound).
Education in Latin had been a major function of monasteries since Ælfric’s time but grammar schools became where order was imposed on spelling. Funding them became a common act of charity by wealthy merchants in Tudor times after the dissolution of the monasteries. Richard Mulcaster, headmaster of Merchant Taylors’ school, is our most influential lexicographer and had a large effect on standardisation of spelling. He published “Elementarie” in 1582, which ends with a list of 8000 “hard words”. Mulcaster does not define any of them, but attempts to lay down a standard spelling for them at a time when English lacked universal standardized spellings. Samuel Johnson and Noah Webster further standardized spelling. Unfortunately, ongoing pronunciation changes mean that four words (below) that once had different vowels are now homophones.

One of the very few spelling rules in English, given to us by Mulcaster, that a final “-e” makes the vowel before the previous consonant long. Teachers call this “the magic e”. The Old English macron was much more useful and more or less intuitive. The majority of vowels in our text have to be sounded from knowledge of the word and there are no rules to help. Pronunciation has diverged even further from speech since Mulcaster’s time. It is no surprise that many children find learning to read and spelling difficult. While they may be described as “dyslexic”, an equivalent term in Chinese and even several Latin-based European scripts is hardly known. Our alphabet is now not fit for purpose. Is spelling reform an option? Between 1934 and 1975, the Chicago Tribune used a number of reformed spellings. Over a two-month spell in 1934, it introduced 80 respelled words, including tho, thru, thoro, agast, burocrat, frate, harth, herse, iland, rime, staf and telegraf. However, it reverted to traditional spellings over the next 40 years. It would make billions of texts and lines of computer code obsolete and how many countries would have to agree?
It turns out that the most valid measure of a person’s intelligence number of unusual words they can pronounce. Vocabulary size may not correspond to most people’s intuition about intelligence, which is more likely to be Sherlock Holmes (or Vera, or Poirot) rapidly processing diverse bits of information into a unified hypothesis about the crime. If you consider this forensic information processing further, it is very much to do with the number and complexity of the abstract ideas you can keep in working memory. Can you pronounce the following 20 words?
gnat once eyes cold chasm redoubt aisle xylem mind against heard bough colonel zeugma knavery hyperbole ephemeral eviscerate aphelion psalter.
The diagram below gives an indication of how spoken and written information is stored in the brain. The implication is that an English speaker has to store a very large number of sound and letter combinations.

Now consider how ideas, speech and writing might be organised in the brain of a Japanese speaker. Basic literacy is reached at about age 13 when the pupil can recognise about 2,300 symbols.

Native speakers can understand very noisy, slurred and accented speech. We can also understand very bad spelling.
